Apparatus for assembling impeller elements



FIG.4.

INVENTOR FRANCIS H. THELEN F. H. THELEN APPARATUS FOR ASSEMBLINGIMPELLER ELEMENTS Filed Oct. 6, 1960 Pie. 5.

@5401. BY f//%/ Sept. 22, 1964 ATTORNEYS United States Patent Ofiice 7Patented Sept. 22, 1964 3,149,378 APEARATUS F83 ASSENBLENG WELLERELEMENTS Francis H. Thelen, Tuiunga, (laiii, assignor to Fuller Company,Catasauqua, Pa, a corporation of Delaware Filed Oct. 6, 1960, Ser. No.61,021 6 Claims. (CI. 18-36) The present invention relates to anapparatus for assembling impeller assemblies in which the drive shaft isadhesively bonded to the impeller element. Heretofore it has been commonpractice to secure the impeller element to the driving shaft by aso-called interference fit in which a shaft of slightly greater diameterthan the bore of the impeller element is forced into the bore of theimpeller element, and the impeller element then keyed to the shaft.However with the use of larger shafts, such as those used in ahigh-pressure, high-speed impeller, such means of securing the imr-ellerelement is not satisfactory since the increase in the shaft diameternecessarily requires an increase in the bore diameter through theimpeller. This reduces the wall thickness of the impeller at the shaftbore and weakens the impeller at that point so that the stress resultingfrom the usual interference type of assembly will either break theimpeller or stretch the metal beyond its elastic limit.

The apparatus of the invention is particularly adapted for use inassembling impeller elements onto drive shafts where the portion of thedrive shaft on which the impeller is mounted is relieved, or is ofslightly less diameter than the diameter of the bore of the impellerelement except for lands adjacent the opposite sides of the impellerelement. Such portion of less diameter provides a space between thelands for receiving a layer of the adhesive agent of appreciablethickness.

The apparatus for assembling the impeller element and driving shaftcomprises a fixture having a base having one face to be attached to theimpeller element and an extension or bushing extending from the otherface. The extension or bushing has a bore to receive the relievedportion of the shaft. An injection fitting for injecting an adhesiveagent into the relieved portion of the shaft, while it is in the bore ofthe bushing, passes through the wall of the fixture and has its innerend communicating with the bore of the fixture.

In assembling the impeller element and drive shaft, the fixture issecured to one side of the impeller element with its bore in exact axialregistry with the bore of the impeller element. The shaft is then placedin the fixture in such position that the lands thereon are located atopposite sides of the injection fitting. The adhesive for bonding theimpeller element to the shaft is then forced under high pressure throughthe injection fitting until the space around the shaft, between thelands, is completely filled with the adhesive under pressure. The shaftis then forced axially through the fixture and into the bore of theimpeller element until the space containing the adhesive is centrallypositioned, axially, in the bore of the impeller element In thisposition the lands at the opposite ends of the layer of adhesive liewitlnn the end portions of the bore of the impeller element and preventleakage of the adhesive axially along the shaft. The adhesive is thenallowed to set, or is cured, if it is of the heat-curable type, to forma strong bond between the impeller element and the drive shaft.

The invention will be further described in connection with theaccompanying drawings in which:

FIG. 1 is an elevational view, partly in section, of an impellerelement-driving shaft assembly assembled using the apparatus of thepresent invention;

FIG. 2 is a vertical sectional view of the assembly of FIG. 1 taken online 22 of FIG. 1;

FIG. 3 is a sectional view showing the assembling fixture attached to animpeller element, with the drive shaft positioned therein;

FIG. 4 is a plan View of the assembling fixture; and

FIG. 5 is a detailed sectional view taken on line 5-5 of FIG. 3.

Referring to the drawings, and first to FIGS. 1 and 2, the impellerelement-drive shaft assembly comprises an impeller element 1, which maybe of any type, but as shown is a lobe of a conventional type of atwo-lobe impeller. It generally is of a figure 8 shape in transversesection and has a central bore 2 for a conventional drive shaft 3 andaxially extending bores 4 and 5 in each end. In order to facilitate theassembly of the impeller element onto the drive shaft, as hereindescribed, the portions of these bores remote from the bore for thedrive shaft are undercut to provide inner shoulders 4 and 5 (FIG. 3).

The opposite sides of the impeller element have projections 6 and 6extending radially outwardly for a slight distance. In operation thelobe cooperates in meshing engagement with a like lobe in the impellerhousing in a well known manner, the projections 6 and 6' making a closefit with the impeller housing and the surface of the cooperating lobe.

The drive shaft is provided with lands 7 and 7' which are spaced apart adistance slightly less than the length of the impeller element at thehub thereof so that, when assembled, the lands will extend into the boreof the impeller element a slight distance at each end, as shown inFIG. 1. The lands 7 and 7' extend outwardly from the main diameter ofthe drive shaft a distance of from about 0.001 to 0.003 inch, andpreferably about 0.002 inch. This provides a space or relieved portionon the shaft of that width between the drive shaft and the im pellerelement for an annular layer of an adhesive bonding agent 8 of thatthickness. The diameter of the lands is slightly greater, up to about0.002 inch greater, than the diameter of the bore 2 of the impellerelement so that it has a pressed fit with the impeller element.

While any suitable adhesive may be used to obtain an adhesive bondbetween the impeller element and the drive shaft, it has been found thatheat-curable resinous epoxy compositions give an excellent bond.Examples of such compositions which have been used are as follows:

Example I Parts by wt. Furane Epocast No. 17A Furane Hardener No. 909 8This is a viscous liquid mixture having slow setting characteristics atroom temperature. It was cured for 12 hours at a temperature between 375and 400 F.

Example 11 Parts by volume Devcon A 9 Hardener 1 This composition hasthe consistency of heavy putty. It was cured at room temperature,approximately 70 F.

Example 111 Parts by wt. Epocast No.295 100 Hardener No. 909 5 This is athixotropic mixture. It was cured for 19 hours at a temperature between375 and 400 F.

Referring now to FIGS' 3 to 5, the fixture F for assembling the impellerelement onto the drive shaft comprises a base member 10 adapted to beclamped against one side of the impeller element during the assemblingoperation. The base member has extending therefrom at the side thereofopposite the side which is to be clamoed 3 to the impeller element, anextension or bushing 11. The bore of the bushing is lined with amaterial 12 having good wearing qualities and preferably having a lowsurface-friction coefiicient. The diameter of bore 13 is 0.002 to 0.004inch larger than the diameter of the lands 7 and 7' of the shaft 3. Theend of the bore 13 is flared outwardly at 12' to facilitate insertion ofthe driving shaft during an assembling operation, as hereinafterdescribed.

The opposite ends of the base members 10 have unthreaded openings 14 and14' through which extend clamping bolts 15 and 15 having laterallyextending toe pieces 16 and 16' extending therefrom at one end. Pins 17and 17 extend through the other or outer ends of the clamping bolts andform handles enabling the bolts to be located in proper position toengage behind the shoulders 4' and when the assembling fixture is to beclamped to an impeller element.

The outer ends of the bolts are threaded and clamping nuts 18 and 18 arethreaded onto them. These nuts preferably have laterally extendingprotuberances so that they may readily be turned by ones hand to threadthem along the bolts.

The surface of the base 10, which is adapted to be clamped against theimpeller element during an assembling operation, has crescent-shapedrecesses 19 and 19 circumjacent the openings 14 and 14'. These recessesprovide spaces for locating pins 20 and 20 which protrude radially fromthe bolts 15 and 15'. When the bolts are rotated in one direction untilthe locating pins engage one end of the crescent-shaped recesses, asshown in FIG. 3, the toe pieces of the bolts are brought behind theshoulders 4' and 5' of the bores 4 and 5 of the impeller element. Whenthe bolts are rotated in the opposite direction, the toe pieces of thebolts are removed from behind the shoulders so that the fixture may beremoved from the impeller element.

The bushing 11 and its liner 12 have a radially extending opening 21into the outer end of which is fitted an injection fitting 22,preferably of the check-valve type.

To assist in locating the fixture in proper position on one end of theimpeller element, a guide or locating member 23 is secured to the faceof the base member which is secured to the end of the impeller bymachine screws 24. This locating member has a projecting stud 25 to bereceived in an opening in the face of the base member to assure that thelocating member is properly located to be received in one of the bores 4or 5 of the impeller element. The sides 26 and 26 of the member 23 arecurved lengthwise and transversely. The width of the locating membertransversely of the base member is substantially equal to the diameterof the'bores 4 and 5, being just sufficiently less to enable easyinsertion of the member into one of the bores. The radius of curvaturelengthwise of the sides 26 and 26' is slightly less than the radius ofcurvature of the bores 4 and 5 so that there is only substantiallylinear contact between those edges of the locating member and bore 4 or5.

In assembling an impeller element onto a driving shaft, the bolts 15 and15 are rotated to a position where their respective clamping toe pieces16 and 16' extend to positions permitting the bolts to pass into thebores 4 and 5 of the impeller. The fixture then is placed against oneend face of the impeller element, with the bore 13 thereof in exactaxial registry with the bore 2 of the impeller element. The bolts arethen turned in the opposite direction until the locating pins 20 and 20'engage the outer ends of the respective crescent-shapedrecesses 19 and19'. This positions the toe pieces 16 and 16' of the bolts bebind theshoulders 4' and 5' of the bores 4 and 5. The clamping nuts 18 and 18'are then turned to cause the bolts to move in a direction away from theimpeller element and to cause the toe pieces to clamp tightly againstthe shoulders 4' and 5'. This effectively clamps the fixture tightlyagainst the end face of the impeller. With the fixture clamped tightlyagainst the end face of the impeller, and with the bore 13 of thefixture in exact axial registry with the bore 2 of the impeller element,the drive shaft 3 is inserted into the outer end of the bore 13 untilthe space between the lands 7 and 7' of the shaft is wholly within thebore 13, with the lands located at opposite sides of the injectionfitting, as shown in FIG. 3. With the drive shaft in this position, theadhesive composition is forced through the injection fitting 21 underhigh pressure into the space defined by the driving shaft, the liner 12and the lands 7 and 7, until the adhesive composition begins to leak outbetween the bushing liner and lands on the shaft. At this time all airwill have been forced from the space and the space completely filledwith the adhesive composition under high pressure. The shaft is thenforced axially through the bushing and into the bore 2 of the impellerelement until it reaches the position shown in dotted lines in FIG. 3,and in full lines in FIG. 1. A suitable tool may be used for thispurpose.

As the shaft 3 and its coating of adhesive are forced into the impeller,both frictional resistance and the shearing action of the edge of theimpeller through which the shaft passes, will peel-01f a certain amountof the adhesive. However, since the bore 13 of the fixture is about0.003 inch greater in diameter than the bore of the impeller, a slightexcess of adhesive is available to prevent this peeling from robbing therequired adhesive from the 0.002 inch relieved portion of the shaft.

Since the diameter of the lands 7 and 7 is slightly greater than thediameter of the bore 2 of the impeller element, a concentric,interference fit will be obtained between the lands and the impellerelement. The adhesive composition forms an annular layer, underpressure, between the drive shaft and the impeller element and isprevented from escaping by the interference engagement of the lands 7and 7' with the impeller element. This assures that there will beintimate bonding throughout substantially the entire area of theopposing faces of the impeller element and the shaft throughout thedistance between the lands.

The adhesive composition is now permitted to set, or if it is of theheat-curable type, is subjected to the proper degree of heat for anadequate length of time to thoroughly cure it. If the adhesivecomposition is of the heatcurable type, and also is one which expandswhen heated, the expansion will cause an even more intimate and strongerbond between the impeller element and the drive shaft.

It is to be understood that various changes may be made in the specificform of the fixture described herein without departing from theinvention or sacrificing any of the advantages thereof.

I claim:

1. A fixture for assembling an impeller element onto a shaft whichcomprises a base member having a face to be secured tightly to one endof an impeller element, an extension or bushing having a bore extendingtherethrough in a direction normal to said face of the base memberextending from the opposite face of the base member through which ashaft to be attached to the impeller may be passed, means at oppositesides of said extension or bushing for securing the fixture to animpeller element, said extension or bushing having an opening extendingthrough its wall and terminating at the bore thereof, and an injectionfitting attached to the extension or bore and having the opening thereofcommunicating with the opening through the wall of the extension orbushing through which an adhesive to secure the impeller to the shaftmay be passed.

2. A fixture as defined in claim 1, in which the means for securing thefixture to an impeller element comprises clamping bolts extendingthrough openings in the base member, each of said bolts having alaterally extending portion adapted to engage behind a portion of animpeller element to be assembled onto the shaft, and means for movingthe bolts longitudinally through the holes in the base member in adirection to move said laterally extending portions towards said basemember.

3. A fixture as defined in claim 2, in which the laterally extendingportions of the bolts are toe pieces extending from the clamping boltsat one side thereof, and which includes means for locating said toepieces in a predetermined position to engage behind a portion of theimpeller element.

4. A fixture as defined in claim 3, in which said locating meanscomprises an arcuate-shaped recess in the base member circumjacent eachof the openings through which the clamping shoulders pass and aprojection extending laterally from said bolts and adapted to be locatedin the respective recesses, the ends of the respective recesses actingas stops for the projections when the projections are located in saidrecesses and the bolts are turned in opposite directions.

5. A fixture as defined in claim 4, in which the clamping bolts aremounted for rectilinear movement through the openings in the base memberand for turning movement only to the extent of the free movement of theprojections in said arcuate-shaped recesses, the end portions of thebolts extending from the face of the base member opposite the face whichengages the impeller element being threaded, and clamping nuts mountedon said threaded portions of the respective bolts.

6. A fixture as defined in claim 1 including a locating memberprotruding from the face of the base member which is to be secured to animpeller element, said locating member being adapted to be received inan opening in the impeller element.

References Cited in the file of this patent UNITED STATES PATENTS421,089 Wood Feb. 11, 1890 1,283,947 Steinle Nov. 5, 1918 1,368,449Myers Feb. 15, 1921 2,082,379 Brittain June 1, 1937 2,226,777 MartinDec. 31, 1940 2,336,159 Bent Dec. 7, 1943 2,423,869 Blessing July 15,1947 2,512,230 Greaves et a1. June 20, 1950 2,618,579 Brajer Nov. 18,1952 2,688,159 Swartz et al. Sept. 7, 1954 2,724,864 Krotz Nov. 29, 19552,923,579 Scheel Feb. 2, 1960 3,061,887 Clarke Nov. 6, 1962

1. A FIXTURE FOR ASSEMBLING AN IMPELLER ELEMENT ONTO A SHAFT WHICHCOMPRISES A BASE MEMBER HAVING A FACE TO BE SECURED TIGHTLY TO ONE ENDOF AN IMPELLER ELEMENT, AN EXTENSION OR BUSHING HAVING A BORE EXTENDINGTHERETHROUGH IN A DIRECTION NORMAL TO SAID FACE OF THE BASE MEMBEREXTENDING FROM THE OPPOSITE FACE OF THE BASE MEMBER THROUGH WHICH ASHAFT TO BE ATTACHED TO THE IMPELLER MAY BE PASSED, MEANS AT OPPOSITESIDES OF SAID EXTENSION OR BUSHING FOR SECURING THE FIXTURE TO ANIMPELLER ELEMENT, SAID EXTENSION OR BUSHING HAVING AN OPENING EXTENDINGTHROUGH ITS WALL AND TERMINATING AT THE BORE THEREOF, AND AN INJECTIONFITTING ATTACHED TO THE EXTENSION OR BORE AND HAVING THE OPENING THEREOFCOMMUNICATING WITH THE OPENING THROUGH THE WALL OF THE EXTENSION ORBUSHING THROUGH WHICH AN ADHESIVE TO SECURE THE IMPELLER TO THE SHAFTMAY BE PASSED.